1. Field
The present disclosure relates to a display device, and more particularly, to a display device in which an organic light-emitting display unit and a reflective liquid crystal display unit are coupled to each other so as to maximize outdoor visibility.
2. Description of the Related Technology
In general, an organic light-emitting display device including a thin film transistor (TFT) is drawing attention since it can be applied to electric and electronic products, such as a digital camera, a video camera, a camcorder, a personal digital assistant (PDA), a smart phone, a thin film television set, an ultra-slim notebook, a tablet PC, a flexible display device, and the like.
The organic light-emitting display device is a self luminescent display device that forms a color by recombining and emitting holes and electrons that are injected into an anode and a cathode at an organic emissive layer (EML), and has a stack structure in which the EML is interposed between the anode and the cathode.
However, since such a stack structure may not obtain highly efficient emissive, the organic light-emitting display device selectively uses an intermediate layer such as a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL) that are disposed between electrodes and the EML.
A liquid crystal display panel is a light receiving display device that does not emit light, but rather receives light incident from outside to display an image.
The liquid crystal display panel displays an image, a number, a character, and the like by injecting liquid crystals between a plurality of substrates, and changing an arrangement of liquid crystal molecules when power is supplied. The liquid crystal display panel may be classified in various ways according to a driving method, a display method, and a display form. In this regard, a thin film transistor (TFT) liquid crystal display panel is a panel in which transistors are uniformly arranged on a substrate.
In particular, a liquid crystal display panel of a semi-transmission structure has excellent visibility characteristics under sunlight. However, power consumption increases, reflectivity is reduced, and the manufacturing process is difficult due to a reduction in an aperture ratio.
The organic light-emitting display device has advantageously a high color recombination rate, high contrast, and wide viewing angles, compared to the liquid crystal display panel. However, the organic light-emitting display device has an outdoor visibility characteristic caused by a polarizing film, and thus visibility of the organic light-emitting display device deteriorates due to a reflected polarizing film. Therefore, the organic light-emitting display device needs a structure capable of securing visibility under sunlight.